Fasting Intervals Linked to Faster Chronic Disease Buildup in Older Adults

Intermittent fasting has been sold as one of the more accessible routes to longer, healthier life. But a study from Karolinska Institutet published in the Journal of Internal Medicine raises a pointed caution: the older you are, the more those long meal gaps may work against you. For people already juggling multiple health conditions or managing frailty in their seventies or eighties, the calculus around meal timing looks meaningfully different from the research most of us have read.

Key takeaways:

• Adults aged 78 and older with daily meal intervals of 14 to 24 hours accumulated chronic diseases faster than those with intervals of 6 to 11.5 hours.
• The association was strongest for cardiovascular and neuropsychiatric (brain and mood-related) diseases, not musculoskeletal ones.
• This is observational research: it shows a link, not a cause. Long gaps may reflect illness-driven appetite loss, not chosen fasting.
• Randomized trials in older populations are urgently needed before any eating-schedule recommendations can be made.

Long Meal Gaps Tied to Faster Chronic Disease Accumulation in Older Adults

The study, published in the Journal of Internal Medicine, found that older adults with the longest daily meal intervals accumulated chronic diseases faster over time than those who ate within a shorter window. Specifically, individuals whose longest daily meal gap fell between 14 and 24 hours showed a faster rate of disease accumulation compared to those with gaps of 6 to 11.5 hours. The association held for total chronic disease burden, and was most pronounced for cardiovascular diseases and neuropsychiatric conditions (a category that includes depression, dementia, and related disorders). Musculoskeletal diseases, such as arthritis or osteoporosis, showed no significant association.

The effect was most pronounced among people aged 78 years and older, a group where nutritional vulnerability and frailty are already common challenges.

Why This Matters for People Managing Multiple Conditions

Most of what we know about intermittent fasting comes from studies in younger or middle-aged adults, where caloric restriction and prolonged fasting windows have often shown metabolic and cardiovascular benefits. Research on intermittent fasting and cardiovascular aging has explored whether these strategies might also delay cardiovascular disease in aging populations, but the evidence has been far from settled. This study suggests the relationship may actually reverse in older cohorts.

For anyone already living with heart disease, depression, or early cognitive decline, the finding that long meal intervals are associated with faster accumulation of those very same disease categories is worth paying attention to. It's also relevant for caregivers and family members trying to understand why an older adult's eating patterns matter beyond simple nutrition. Circadian rhythm disturbances common in the elderly are already linked to hypertension, cardiac insufficiency, and impaired immune function; erratic or widely spaced meal timing may compound those vulnerabilities.

Researcher Adrián Carballo Casla put it plainly:

"Much of the research on fasting has been conducted in younger or middle-aged populations. Our findings suggest that the associations may be different in older adults, particularly among the oldest age groups."

How the SNAC-K Study Tracked Eating Habits Over 15 Years

The research drew on data from the Swedish National Study on Aging and Care in Kungsholmen (SNAC-K), a long-running cohort based in Stockholm. The sample included 2,981 participants aged 60 and older at the study's start, followed for up to 15 years. Meal interval duration was estimated from self-reported eating times over a 24-hour period, which gave the team a picture of habitual patterns rather than a one-off snapshot.

Because the study is observational, the investigators measured existing eating habits rather than assigning specific meal schedules. This design is well suited to tracking real-world behavior over a long period, but it also means the study cannot establish cause and effect. Much of the foundational intermittent fasting research on longevity has similarly relied on observational or short-term trial designs, making it difficult to draw firm conclusions about long-term outcomes in any age group.

What Longer Meal Gaps Could Mean for Your Health Routine

For a healthy older adult who is maintaining weight and has no frailty concerns, the study's authors note that a particular eating schedule may be well tolerated. This is not a finding that says everyone over 60 should eat constantly or abandon any structure around meals.

The concern is more specific: if you or someone you care for is older, has experienced unintentional weight loss, has diabetes, or is already managing multiple chronic conditions, long gaps between meals may deserve closer medical attention. That's a different question from whether a robust 65-year-old benefits from time-restricted eating. General fasting guidance for longevity often points to a simple 12-hour overnight fast as a reasonable starting point for most people, and this study doesn't contradict that for healthier adults. The signal here is specifically about vulnerability at older ages and higher disease burdens.

None of this translates into a proven intervention. The study doesn't tell us that changing meal timing will slow disease accumulation. That question awaits the kind of randomized trial that has not yet been conducted in this population.

Unanswered Questions and Study Limitations

The biggest caveat is one the researchers themselves flag: the study cannot determine whether long meal gaps independently caused faster disease accumulation, or whether the relationship runs in the opposite direction. Older adults who are already ill or experiencing appetite loss naturally end up eating less frequently. It's entirely possible that some or all of the signal reflects illness driving long gaps, rather than long gaps driving illness.

The observational design also cannot account for all the other differences between people who habitually eat within a short window and those who do not. Socioeconomic factors, activity level, medication use, and baseline health all vary across those groups. Existing reviews of fasting research for aging outcomes have consistently called out the lack of high-quality long-term randomized trials as the central limitation in the field; this study does not resolve that gap, but it does sharpen the argument for why those trials are needed specifically in older populations.

The Case for Randomized Trials in Older Populations

The study authors point to randomized clinical trials as the necessary next step, testing specific eating schedules in older adults and measuring outcomes including muscle strength, nutritional status, blood glucose, cardiovascular health, and cognitive function. That kind of evidence would begin to separate the question of whether meal timing causes changes in health from the question of whether health changes alter meal timing.

Circadian-based interventions like time-restricted eating show genuine promise for metabolic and cardiovascular health in younger groups, but most studies remain short-term and in select populations. Scaling that research to include frail older adults with multiple existing conditions is a meaningfully harder task, and it's one the field has not yet seriously attempted.

Common Questions

Does this mean older adults should avoid intermittent fasting entirely? Not necessarily. The study suggests that very long meal gaps may be problematic for older adults, especially those aged 78 and older with existing health conditions or frailty. For healthier older adults without those vulnerabilities, the evidence isn't conclusive either way. Talk to a doctor before changing meal timing at this stage of life.

Could the long meal gaps just reflect illness, not cause it? Yes, that's a real possibility the researchers acknowledge. Appetite loss and reduced eating frequency are common in people who are already sick. The observational design cannot separate cause from consequence, which is why randomized trials are the needed next step.

Which diseases were most affected? The association was strongest for cardiovascular diseases and neuropsychiatric conditions (which include depression and dementia-related disorders). No significant link was found for musculoskeletal diseases like arthritis.

References

1. Luis Kalmbach, David Abbad‐Gomez, Giorgi Beridze, et al. (2026). Habitual fasting duration and accelerated multimorbidity in older adults. Journal of Internal Medicine. https://doi.org/10.1111/joim.70150
2. Mualla Ozcan, Mahmoud Abdellatif, Ali Javaheri, Simon Sedej (2024). Risks and Benefits of Intermittent Fasting for the Aging Cardiovascular System. Canadian Journal of Cardiology. https://doi.org/10.1016/j.cjca.2024.02.004
3. Mehrshad Sadria, Anita T. Layton (2021). Aging affects circadian clock and metabolism and modulates timing of medication. iScience. https://doi.org/10.1016/j.isci.2021.102245
4. Valter D. Longo, Maira Di Tano, Mark P. Mattson, Novella Guidi (2021). Intermittent and periodic fasting, longevity and disease. Nature Aging. https://doi.org/10.1038/s43587-020-00013-3
5. Fasting for Longevity? A Doctor Explains the Science | The Well by Northwell. thewell.northwell.edu. https://thewell.northwell.edu/healthy-living/fasting-for-longevity
6. Dara L. James, Nanako A. Hawley, Alex E. Mohr, et al. (2024). Impact of Intermittent Fasting and/or Caloric Restriction on Aging-Related Outcomes in Adults: A Scoping Review of Randomized Controlled Trials. Nutrients. https://doi.org/10.3390/nu16020316
7. (2026). Circadian Rhythms, Metabolic Disorders, and Cardiovascular Aging: Molecular Crosstalk and Clinical Translation. aging and disease. https://doi.org/10.14336/ad.2026.0314